Welcome to our book review site go-pdf.online!
You may have to Search all our reviewed books and magazines, click the sign up button below to create a free account.
Analysis and Comparison of Power Electronic Converters with Electronic Isolation
With the continual increase in the global energy consumption, grows the demand on the power capacity, efficient production, distribution and utilization of the electrical energy generated. The role of power electronics in such contexts has been of great importance not only for the traditional power generator systems but also for the decentralized renewable energy generation, like solar and wind power. Several innovations can be observed in the field of power systems for renewable energy sources based on power electronics. Improvements can be identified regarding for example control techniques, semiconductor devices, electromagnetic components and also topologies. Such developments allow spec...
Investigation on Performance Advantage of Functionally Integrated Magnetic Components in Decentralised Power Electronic Applications
The functional integration of magnetic components is a known technique in order to enable high power densities for power electronic converters. Magnetic components are mandatory in many power electronic converters and many topologies demand more than one magnetic component. Therefore, the functional integration of magnetic components allows realising several magnetic functions within one component. This technique promises lower total size, losses and costs without switching frequency increase. There are several examples in the literature for coupled inductors, common-differential-mode chokes or transformer-inductor components. One centralised question of this work is to explore the performan...
Development of Brushless Self-excited and Self-regulated Synchronous Generating System for Wind and Hydro Generators
In this work, a developed model of brushless synchronous generator of wound rotor type is designed, analyzed by FEM, practically applied and investigated. A comparison of results with conventional machines is also performed. The presented machine can be applied for multi-pole wind/ hydro generators or double-poles diesel-engine generators. It is self-excited by residual magnetism and a connected capacitor. It is also self-regulated by making use of fluctuations at load or limited speed changes. The generated voltage may last at extended speed range by arranging a generating system with variable capacitance. By eliminating the permanent magnets or advanced manufacturing technology of rotor po...
Design, Control, and Harmonic Compensation for Stand-Alone and Grid-Connected Voltage-Source Converters: Simulation and Experimental Validations
Voltage source converters (VSCs), among other power converters, play a crucial role in supplying power to both local loads and the grid at the PCC. During stand-alone operation, VSCs ensure stable power for loads by regulating the output voltage. In grid-connected mode, the regulation shifts to controlling output current, such as converter side current (CSC) or grid side current (GSC), to inject sinusoidal current into the electrical grid. The nonlinear characteristics of the loads connected to the power converters result in significantly distorted output voltages. This capability is crucial for applications such as uninterruptible power supply (UPS), emphasizing the importance of precise ou...
Short Circuit Requirements of Power Converters based upon Wide-Bandgap Semiconductors
In power electronics designs, the evaluation and prediction of potential fault conditions on semiconductors is essential for achieving safe operation and reliability, being short circuit (SC) one of the most probable and destructive failures. Recent improvements on Wide-Bandgap (WBG) semiconductors such as Silicon Carbide (SiC) and Gallium nitrite (GaN) enable power electronic designs with outstanding performance, reshaping the power electronics landscape. In comparison to Silicon (Si), SiC and GaN power semiconductors physically present smaller chip areas, higher maximum internal electric fields, and higher current densities. Such characteristics yield a much faster rise of the devices’ internal temperatures, worsening their SC performance. In this way, this dissertation consists of a comprehensive investigation about SC on SiC MOSFETs, GaN HEMT, and GaN E-HEMT transistors, as well as contextualizing their particularities on SC performance by comparison with that of Si IBGTs. Moreover, an investigation towards how to prevent SC occurrences besides a review of available SC protection methods is presented.
Investigation of Reliability Aspects of Power Semiconductors in Photovoltaic Central Inverters for Sunbelt Regions
High reliability and system lifetimes in the range of 30 years are essential for renewable energy systems such as photovoltaic power plants to minimise costs for the generated electric energy. At the same time such systems are used in regions with high solar irradiance and also harsh environmental conditions. Therefore, designs for photovoltaic inverters need to meet not only the key design criteria of high conversion efficiency but also need to be very robust and at the same time meet challenging cost targets. In this dissertation aspects concerning the lifetime and reliability of power semiconductors in photovoltaic central inverters are investigated. On key topic of the dissertation is the measurement of the voltage dependent failure rate due to cosmic radiation induced single-event-burnout of SiC and Si power semiconductors. The second topic is the development of a system level simulation to quantify the stress on the power semiconductors in a PV central inverters in various regions of the world. Further topics are the investigation of improved control concepts for the cooling system of PV central inverters and the monitoring of IGBT temperatures during converter operation.
Maximierung der Leistungsdichte von selbstgeführten hochfrequenten Energiewandlern auf Basis ultraschneller Wide-Bandgap Bauelemente
Um Kosten zu reduzieren und marktfähig bleiben zu können, geht auch in der Anwendung von selbstgeführten Energiewandlern der Trend hin zur Miniaturisierung. Vor allem kleinere Gehäuse und Kühlkörper sowie kleinere Drosseln und Filterelemente können den Materialeinsatz erheblich reduzieren und die Kosten senken. Dies führt dazu, dass bei gleichbleibender Performance die Leistungsdichte des gesamten Produktes maximiert werden muss. Durch den Einsatz von effektiveren Bauelementen kann dies erreicht werden. Zudem können beispielsweise durch höherer Taktfrequenzen Drosseln und Filterelemente kleiner dimensioniert werden.
Die aktuelle Aufbau- und Verbindungstechnik (AVT) stößt bei der Lösung dieser Herausforderungen jedoch an ihre Grenzen, weswegen neue Ansätze erforderlich sind. Ein neuer Ansatz in der Leistungselektronik ist die Einbettung von Bauelementen in die Leiterplatte. Im Rahmen dieser Arbeit wurde diese Technologie mit neuen Siliziumcarbid Leistungshalbleiterschaltern untersucht und mit der konventionellen diskreten AVT verglichen. Zudem wurden die Einflüsse ultraschneller Schaltvorgänge sowie von parasitären Elementen auf die Peripherie untersucht.
Gönül Verip Sevdiğim - Dede Korkut Hikayelerinden Seçmeler
Oğuzların yaşantısına ve kahramanca mücadelelerine değinen Dede Korkut hikâyeleri, 14. asırda yazıya geçirilmiştir. Oğuzlar, şiir ögeleri bulunmakla birlikte, yer yer modern roman anlatımına yaklaşan düz yazı stiliyle maceralarını kayıt altında almışlardır. Halk hikâyelerine benzer bir anlatım özelliği taşıyan, millî bir destan havasındaki bu hikâyelerde alp tipinin tipik davranışları görülür. İnsanı sürükleyip götüren bu hikâyelere coşkun bir söyleyiş hâkimdir. Baş döndürücü bir hareketlilikle gelişen, sonucunun ne olacağı konusunda insanı meraklandıran olaylar, canlı tabiat tasvirleri eşliğinde verilir. Dede Korkut hikâyelerinin kendine has kıvrak, yalın ve açık bir dili ve üslubu vardır. Bu üslup, özlü çıkarımlara sahip atasözleri ve vecize özelliği taşıyan bilgece ifadelerle de süslenmiştir. Bu hikâyelerin, çocuklarımızın ruh dünyasına iyi yönde etki edeceğini umuyoruz.
